I get that and agree, and in this day and age it would seem unheard of to not have DNA, so I guess my thought then is if DNA is able to rule people out or narrow in on people - with no arrest then maybe that means there is something "wrong" with the DNA that wouldn't allow it to hold up in court, hence the need for "that one tip." Either that, or perhaps the DNA allows them to identify a family but there is both a father and son that would "fit the bill" and thus far they have no way to discount one over the other.
Well, you’d think that in JBR’s case they would have had the guts to at least preserve DNA, right? Instead, it became the travesty of justice, with powerful, rich suspects and police à la Keystone Cops.
If that case is not solved, why should we accept every other would be?
There should be DNA...
Options:
I assume that the ISP was smart and collected it from everywhere, the bridge, the spit, around the bodies, the bodies, and the pathologist did his job, too. I have to hope that real DC is calm, collected and rational.
So what can be wrong with the DNA?
1) My first thought, somehow, it disappeared. Or the chain of custody was broken.
I assume that ISP don’t handle the analysis themselves. Whoever they gave it to (who could it be?) did not return it and is merely giving them reports.
Or, it could be stolen en route. Or, the lab had the power outage.
But is it possible to assume that they had DNA at the beginning, and don’t have now?
Using Occam’s razor, this is my first guess. They planned to give it to Parabon, they had it, but in two years, they somehow lost it. MOO.
2) If they still have it, the viable DNA is:
Buried in the mess of others
Really destroyed by the perp
Who knows which is which?
3) In non-endogamous communities, a father and a son share 50% of the same DNA, the same Y, and usually, have different mito DNA. Granted, mito DNA might be the same if both father’s and son’s maternal lines came from the same woman (can happen in small villages), but it would be still uncommon. So it is not difficult to discriminate between the two, especially if you phase son’s DNA against his mom’s DNA. Even in partial, you could, potentially, figure out whose DNA it is. Gedmatch has an interesting function, Lazarus, that allows, if you have 50% of a person’s DNA, reconstruct most of it, using siblings, cousins and children. (I think it can be used if you have a huge family, a suspect and a partial DNA. In principle, an interesting thingy).
Another version - ISP has DNA from the bridge, and LE know who BG is, but it does not match DNA from the killing place. So they need a witness to the killing.